In recent years, an electric vehicle, a hybrid vehicle, a fuel cell vehicle and the like have received attention as an environmentally-friendly vehicle. On these vehicles, a motor that generates driving force for traveling as well as a power storage device that stores electric power supplied to the motor are mounted. The hybrid vehicle further has an internal combustion engine mounted thereon as a power source, together with the motor. The fuel cell vehicle has a fuel cell mounted thereon as a direct current (DC) power supply for driving the vehicle.
Among these vehicles, a vehicle is known in which a vehicle-mounted power storage device for driving the vehicle can be charged from a power supply in ordinary households. For example, a power supply outlet provided at home is connected to a charging port provided at the vehicle by using a charging cable, so that electric power is supplied from the power supply in the ordinary households to the power storage device. It is noted that the vehicle in which the vehicle-mounted power storage device can be charged from the power supply external to the vehicle will also be referred to as “plug-in vehicle” hereinafter.
The standard for the plug-in vehicle is defined in “SAE Electric Vehicle Conductive Charge Coupler” (Non-Patent Document 1) in the United States of America, and in “Electric Vehicle Conductive Charging System, General Requirements” (Non-Patent Document 2) in Japan.
In “SAE Electric Vehicle Conductive Charge Coupler” and “Electric Vehicle Conductive Charging System, General Requirements,” the standard for a control pilot is defined as an example. The control pilot is defined as a control line that connects, via a control circuit on the vehicle side, a ground of the vehicle and a control circuit of EVSE (Electric Vehicle Supply Equipment) for supplying electric power from an on-premises wiring to the vehicle, Based on a pilot signal communicated through this control line, a connection state of the charging cable, whether or not electric power is supplied from the power supply to the vehicle, a rated current of the EVSE and the like are determined,    Patent Document 1: Japanese Patent Laying-Open No. 9-161882    Non-Patent Document 1: “SAE Electric Vehicle Conductive Charge Coupler,” (the United States of America), SAE Standards, SAE International, November, 2001    Non-Patent Document 2: “Electric Vehicle Conductive Charging System, General Requirements,” Japan Electric Vehicle Association Standard (Japan Electric Vehicle Standard), Mar. 29, 2001